Beat the game with every character and the 7th character -"Super Sonic" - will be opened.

Play as Tails:

After he is obtained, use Controller 2 to play as Tails.

Mega Characters:

Beat the game with every character, including Super Sonic. Return to the character selection screen. Now whatever character you select will be 'Mega' - Mega Sonic, Mega Tails, etc. They'll now be much faster and invincible.

Hidden artwork:

Put the game disc in a PC CD-ROM drive to find additional art images from the game.